Chemical imaging has a powerful capability for material characterization, process monitoring, quality control and disease-state determination. Chemical imaging combines digital imaging and molecular spectroscopy techniques, which can include Raman scattering, fluorescence, photoluminescence, ultraviolet, visible and infrared absorption spectroscopes, among others.
A Fiber Array Spectral Translator (referred to herein as “FAST”, “FAST fiber bundle”, “FAST array”, and/or “FAST device”) device when used in conjunction with a photon detector allows massively parallel acquisition of full-spectral images. A FAST device can provide rapid real-time analysis for quick detection, classification, identification, and visualization of the sample. The FAST technology can acquire a few to thousands of full spectral range, spatially resolved spectra simultaneously. A typical FAST array contains multiple optical fibers that may be arranged in a two-dimensional (“2D”) array on one end and a one dimensional (“1D”) array (i.e., linear) array on the other end. The linear array is useful for interfacing with a spectrograph and a photon detector, such as a charge-coupled device (“CCD”). The two-dimensional array end of the FAST is typically positioned to receive photons from a sample. The photons from the sample may be, for example, absorbed by the sample, emitted by the sample, reflected off the sample, refracted by the sample, fluoresced from the sample, or scattered by the sample. The scattered photons may be Raman photons.
In a FAST spectrographic system, photons incident to the two-dimensional end of the FAST may be focused so that a spectroscopic image of the sample is conveyed onto the two-dimensional array of optical fibers. The two-dimensional array of optical fibers may be drawn into a one-dimensional distal array with, for example, serpentine ordering. The one-dimensional fiber stack may be operatively coupled to an imaging spectrograph of a photon detector, such as a charge-coupled device so as to apply the photons received at the two-dimensional end of the FAST detector rows of the photon detector. Software may be used to extract the spectral/spatial information that is embedded in a single CCD image frame.
One advantage of this type of apparatus over other spectroscopic apparatus is speed of analysis. A complete spectrographic imaging data set can be acquired in the amount of time it takes to generate a single spectrum from a given material. Additionally, the FAST device can be implemented with multiple detectors. The FAST device allows for massively parallel acquisition of full-spectral images. A FAST fiber bundle may feed optical information from its two-dimensional non-linear imaging end (which can be in any non-linear configuration, e.g., circular, square, rectangular, etc.) to its one-dimensional linear distal end input into the entrance slit of a spectrograph.
FAST holds potential for acquiring hundreds to thousands of full spectral range, spatially-resolved spectra, such as Raman spectra, substantially simultaneously. Therefore, a FAST device may be used in a variety of situations to help resolve difficult spectrographic problems.
Despite its potential for quick acquisition of images, traditional FAST suffers from low fidelity imaging. Spatial parallelization of FAST allows for more fibers to be imaged at the entrance slit of a dispersive spectrograph. This is accomplished by placing more than one column of fibers spatially offset in parallel at the entrance slit. Spatial parallelization of FAST, however, introduces spectrally overlapping regions between dispersed columns of fibers at the detector focal plane. Therefore, there exists a need for a system and method that provides for quick image acquisition without spectral overlap.